The present invention concerns a multifunctional labyrinth seal support disk for a turbojet engine rotor. As is well known in the art, turbojet engine and turbine rotor wheels typically define a plurality of axially extending grooves in the periphery which receive roots of the rotor blade.
In order to ensure the maximum operating efficiency of the turbojet engine, leakage of the gases passing over the rotor blades must be minimized. It is known to provide a labyrinth seal between a rotor wheel and an adjacent stator vane structure. The stator vanes are usually located upstream of the associated turbine wheel and serve to direct the flow of gases onto the rotor blades.
The axial grooves defined in the periphery of the rotor wheel typically have a "fir-tree" cross-sectional shape which corresponds to that of the root of the rotor blade such that, when the root is axially slid into the grooves, the interlocking grooves prevent any radial movement of the blade with respect to the wheel. Quite obviously, means must be provided to also prevent axial movement of the blade with respect to the rotor wheel. Many attempts have been made to simplify the attachment of the rotor blades and the labyrinth seals to the rotor wheels in order to achieve both a greater simplicity in assembly and improve resistance to the operational variations of the turbine. The operational variations of the turbine, especially a turbojet engine, tends to loosen the fastening means and, consequently, to increase the component wear, which, in turn, increases the dynamic imbalance of the engine. Typical of such attempts are the systems shown in U.S. Pat. Nos. 3,832,092 and 3,034,298.
French Pat. No. 2,324,873 discloses a system which utilizes an upstream flange and a downstream flange, each incorporating labyrinth seal means, to attach the rotor blades to the rotor wheel. The downstream flange also incorporates an annular portion having openings which are engaged by projections extending from the downstream end of the blade roots. Thus, the downstream flange prevents the rotor blade from moving in an upstream direction with respect to the rotor wheel, while the upstream flange locks the blades and prevents them from moving in a downstream direction with respect to the rotor wheel. The flanges are prevented from rotating by stubs which are kept in place by pins fixed in place by a seal component welded to the flange.
While this design has eliminated many of the drawbacks of the previous systems, it has achieved these results at the expense of simplicity. The numerous small parts, such as bosses and pins, coupled with the need for welding a seal component renders the initial assembly and any subsequent maintenance time consuming and expensive.